Urban Land Conversion Reduces Soil Organic Carbon Density Under Impervious Surfaces

Abstract

The soil organic carbon (SOC) pool is the largest carbon (C) pool in terrestrial ecosystems (Grimm et al., 2008). SOC loss due to land-use change is a major contributor to anthropogenic CO 2 emissions (Piao et al., 2009). Urbanization is among the most prominent land-use changes in the 21st century (Hansen et al., 2005;Kuang, 2020), and the expansion of impervious surface area (ISA), which is an artificially hardened surface characterized by buildings, roads, etc., could cause intensive soil disturbances (Montague & Kjelgren, 2004). The global ISA area is approximately 4.5 × 10 5 to 5.8 × 10 5 km 2 (Kuang, 2019;Kuang, Zhang, et al., 2021;Lehmann & Stahr, 2007), and the built-up area is projected to triple in the first half of the 21st century (Seto et al., 2012). China's urbanization rate is twice the world average, and 67% of its urban area is covered by ISAs, which is higher than the global average (Kuang, 2019;Kuang et al., 2020).

The patterns of soil nitrogen stocks and C : N stoichiometry under impervious surfaces in China

“…and PSA types (trees, shrubs, herbs, bare ground, vegetable plots, etc.). Detailed descriptions of the cities and sample sties can be found in Ding et al (2023).…”

“…To evaluate this theory, we compared the mean intercity C : N stoichiometry dissimilarity and the mean intra-city C : N stoichiometry dissimilarity between the ISA and PSA. (Ding et al, 2023). The background land-use type shows the regional dominant land-use and land-cover type where the cities are located.…”

“…It also contains geographical coordinates of sampling locations as well as spatial pattern layer files of N ISA density and C : N ISA in China. This dataset is available from the National Cryosphere Desert Data Center (https://doi.org/10.12072/ncdc.socn.db2851.2023) (Ding et al, 2023). Our results were comparable to, or moderately lower than, the previously reported topsoil (0-20 cm) N ISA contents and densities in Chinese cities (Table 1), including Beijing (0.34 ± 0.06 g kg −1 vs. 0.37-0.61 g kg −1 ) Zhao et al, 2012), Nanjing (0.13 ± 0.15 g kg −1 vs. 0.49 g kg −1 ) (Wei et al, 2014b), and Yixing (0.15 ± 0.01 kg m −2 vs. 0.25 kg m −2 ) (Wei et al, 2014a).…”

“…These findings indicate the ISA soil had a unique N distribution pattern, possibly as the result of intensive disturbances during land conversion. The dataset "Observations of soil nitrogen and soil organic carbon to soil nitrogen stoichiometry under the impervious surfaces areas (ISA) of China" is available from the National Cryosphere Desert Data Center (https://doi.org/10.12072/ncdc.socn.db2851.2023) (Ding et al, 2023).…”

“…The two panels comprising part (a) show spatial distribution of the sampled cities. The numbers in the map are the IDs of the studied cities, which can be used to retrieve detailed information of the sample sites from the online dataset of this study(Ding et al, 2023). The background land-use type shows the regional dominant land-use and land-cover type where the cities are located.…”